Applicants"" invention relates to an apparatus and method to monitor the movement along one or more axes of robotic accessors moveably disposed within a data storage and retrieval system.
Automated media storage libraries are known for providing cost effective access to large quantities of stored media. Generally, media storage libraries include a large number of storage slots in which are stored data storage media. The portable data storage media are typically housed in a portable container, such as a tape cartridge, an optical cartridge, a disk cartridge, and the like. One (or more) accessors typically access the data storage media from the storage slots and deliver the accessed media to a data storage drive for reading and/or writing data on the accessed media. Suitable electronics operate the accessor(s) and operate the data storage drive(s) to transmit to, and/or to receive data from, an attached on-line host computer system.
In a conventional automated media storage library, the storage slots are arranged in a planar orthogonal arrangement forming a xe2x80x9cwallxe2x80x9d of storage slots for holding data storage media. The plane may be a flat plane, or may be a cylindrical plane. To double the storage capacity, two xe2x80x9cwallsxe2x80x9d of storage slots may be provided on either side of the accessor.
A number of different companies manufacture automated media storage libraries today, each model displaying various different features. One example is the IBM 3584 Media Storage Library. Some of the automated media storage libraries have dual or multiple accessors to provide a level of redundancy and/or improved performance.
It is advantageous to monitor the placement of portable data storage cartridges within a data storage and retrieval system. Such monitoring can assist to inventory portable data storage cartridges, prevent collisions between accessors and improperly stored portable data storage cartridges, verify proper storage of portable data storage cartridges, and/or verify proper retrieval of portable data storage cartridges. Prior art apparatus and methods utilize path sensors consisting of an emitter and a detector, where a set of such emitters/detectors is disposed at either end of each column/row of storage cells in the library. Such prior art apparatus and methods require the use of many such emitters and detectors. What is needed is an apparatus and method to accomplish these monitoring functions using fewer emitters and detectors. Needless to say, decreasing the number of required emitters and detectors lowers both hardware and maintenance costs.
Applicants"" invention includes an accessor which includes at least one emitter disposed at a first position on the accessor, the top portion for example, where that first emitter is capable of emitting first electromagnetic radiation, in combination with at least one receiver disposed at a second position on that accessor, the bottom portion for example, where that receiver is capable of detecting that first electromagnetic radiation. In certain embodiments, Applicants"" accessor further includes a second emitter disposed at a third position on the accessor, where that second emitter is capable of providing second electromagnetic radiation, in combination with a second receiver disposed at a fourth position on the accessor, where that second receiver is capable of detecting the second electromagnetic radiation.
Applicants"" invention further includes an automated data storage and retrieval system which includes one or more of Applicants"" accessors moveably disposed therein. Applicants"" invention further includes a method using Applicants"" accessor to assist inventorying the portable data storage cartridges removeably disposed within one or more storage slots in Applicants"" data storage and retrieval system. Applicants"" invention further includes a method using Applicants"" accessor to prevent collisions between Applicants"" accessor and one or more portable data storage cartridges improperly disposed within one or more of the afore-described storage slots.
Applicants"" invention further includes a method using Applicants"" accessor to verify the proper storage of a portable data storage cartridge in one of the afore-described storage slots. Applicants"" invention further includes a method using Applicants"" accessor to verify the proper retrieval of a portable data storage cartridge from one of the afore-described storage slots.
Applicants"" invention further includes a data storage and retrieval system comprising a computer useable medium having computer readable program code disposed therein for implementing Applicants"" method to inventory portable data storage cartridges disposed in storage slots disposed in one or more vertical columns/horizontal rows (collectively referred to as xe2x80x9ccolumnsxe2x80x9d herein). Applicants"" invention further includes a data storage and retrieval system comprising a computer useable medium having computer readable program code disposed therein for implementing Applicants"" method to prevent a collision between an accessor and one or more portable data storage cartridges improperly disposed in one or more storage slots disposed in one or more vertical or horizontal columns.
Applicants"" invention further includes a data storage and retrieval system comprising a computer useable medium having computer readable program code disposed therein for implementing Applicants"" method to monitor the retrieval of a portable data storage cartridge from a storage slot disposed in a vertical or horizontal column. Applicants"" invention further includes a data storage and retrieval system comprising a computer useable medium having computer readable program code disposed therein for implementing Applicants"" method to monitor the insertion of a portable data storage cartridge into a storage slot disposed in a vertical or horizontal column.